Centrifugation device

ABSTRACT

A centrifugation device comprising a combined sample chamber and slide holder adapted to be mounted, with a microscope slide ( 26 ), in a centrifuge in a predetermined position, after placing a fluid biological sample containing cells in the sample chamber. The device comprises an integrally moulded body ( 10 ) affording a base ( 14 ) which engages the microscope slide, and also affording a back plate ( 14 ) connected with the base plate by an integral hinge ( 22 ) a latch mechanism formed integrally with the remainder of the device is arranged, when the back plate ( 14 ) is closed against the rear of a microscope slide ( 26 ) engaged with the base ( 14 ), to locate the slide between the base and the back plate and to hold the back plate in this closed position until fracture of a retaining element from the integrally moulded body. Thus the device can be used once only. The base includes an aperture communicating with the sample chamber and carries an elastomeric gasket ( 26 ) for sealing the edges of the aperture with respect to the surface of the microscope slide. The material of the gasket ( 20 ) includes an oil component which, in use, forms an oil film on the microscope slide where the gasket contacts the slide, which can act as a barrier to aqueous fluid and prevents migration of such fluid past the region of the slide contacted by the gasket.

RELATED APPLICATIONS

This is a U.S. national phase of PCT/GB2003/003524 filed 13 Aug. 2003,claiming priority from GB 0301047.7 filed Jan. 16, 2003.

BACKGROUND

THIS INVENTION relates to a centrifugation device comprising a combinedsample chamber and slide holder adapted to be mounted, with a microscopeslide, in a centrifuge in a predetermined position, after placing, inthe sample chamber, a fluid biological sample containing cells, thedevice being so-arranged that when the centrifuge is operated, a thinlayer—ideally a monolayer of cells is deposited from the fluid onto apredetermined deposition area on the glass microscope slide. Such acentrifugation device is herein referred to as being “of the kindspecified”.

Various forms of centrifugation device of the kind specified have beenknown in the past. Examples of such devices are disclosed, for example,in U.S. Pat. Nos. 4,391,710; 4,696,743; 4,853,188 and 4,874,582 andEuropean Patents Nos. 0184374 and 0047840. Some examples have beenreusable, that is to say it was possible and intended that after thedevice had been used to deposit cells from a fluid sample onto a firstmicroscope slide, and the slide removed, the device could be cleaned, afresh slide fitted, a fresh fluid sample placed in the sample chamberand the device again placed into the centrifuge and so on indefinitely.In these arrangements the slide is, of course retained by a releasableand re-attachable clip of some description. Some later centrifugationdevices of the kind specified were of the single-use type, that is tosay they were designed in such a way that they could not, or could notconveniently, be used more than once, thereby avoiding contaminationproblems resulting from improper cleaning procedures between uses. Inview of their inevitably disposable nature, devices of the lattercharacter have generally been largely of plastics in order to minimiseproduction costs.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide an improvedcentrifugation device of the single use type.

According to one aspect of the present invention there is provided acentrifugation device as herein defined comprising an integrally mouldedbody affording a base adapted for engagement with a microscope slide,structure on one side of the base defining a chamber for a fluid sample,with an opening for the introduction of fluid to said chamber, the baseincluding an aperture and carrying a means for sealing the edges of suchaperture with respect to the surface of a microscope slide placed acrossthe base, or for allowing the passage of liquid but obstructing thepassage of cells, the centrifugation device further including a backplate connected with the base plate by an integral hinge and a latchmechanism formed integrally with the remainder of the device andarranged, when the back plate is closed against the rear of a microscopeslide engaged with the base, to locate the slide between the base andthe cover plate and to hold the cover plate in this closed positionuntil fracture of a retaining element from the integrally moulded body.

The catch arrangement preferably comprises a detent carried by the backplate adjacent the free edge of the latter and which, in operation,co-operates, in the closed position of the device, with a complementarylatch carried by the body of the device and connected with said body byan integral live hinge, the catch arrangement further comprising ashield element which, in the condition of the device before use, issecured in a position in which it extends over the complementary latchat a predetermined distance from the integral live hinge of the saidcomplementary latch, the arrangement being such that in the closedposition, with the shield element still attached, the detent on the backplate is retained between the shield element and the complementary latchand the shield element counteracts a turning moment applied to thecomplementary latch as a result of tension in the back plate detent,whilst on breaking of a frangible retaining element holding the shieldmember in position relative to the device body, the shield element isable to move away from said complementary latch allowing the latter toswing away from the back plate detent for release of the back platedetent to allow the back plate to swing away from the body of thedevice, and to allow removal of the microscope slide.

The complementary latch may be provided with a retaining arm whichengages a face of the detent on the back plate to push the detent acrossthe abutment face of the latch as the latch tilts outwardly andbackwards during the release of the detent after rupture of theconnection of the shield member with the body part, and thus to ensurerelease of the detent from the latch.

BRIEF DESCRIPTION OF THE DRAWINGS

An embodiment of the invention is described below by way of example withreference to the accompanying drawings in which:

FIG. 1 is a perspective view, from the rear and above, of acentrifugation device in accordance with the invention in the conditionin which a back plate is closed against a body part with a microscopeslide located therebetween;

FIG. 2 is a view in vertical section through the device and microscopeslide of FIG. 1;

FIG. 3 is a perspective view corresponding to FIG. 1 but showing thedevice with the back plate in an open position in relation to the bodypart, without the microscrope slide;

FIG. 4 is a perspective view corresponding to FIG. 3 but from the frontand below;

FIG. 5 is a perspective view from the rear and below of the device withthe back late in an open position with respect to the body part of thedevice;

FIG. 6 is a partial view in horizontal section, and to an enlargedscale, through the device of FIGS. 1 to 4, along the line VI-VI in FIG.1 showing details of the catch arrangement, in the closed condition ofthe back plate,

FIG. 7 is a corresponding partial section of view in the open conditionof the back plate and

FIG. 8 is a fragmentary rear elevation view, also to an enlarged scale,of the body part of the device showing the parts of the catcharrangement carried thereby.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to FIGS. 1 to 4, a centrifugation device in accordance withthe present invention comprises a body part 10 and a back plate 12formed integrally with one another by moulding in a suitable plasticsmaterial such as polypropylene, the back plate 12 being connected withthe body part 10 by way of an integral “living hinge” 22. As shown inFIGS. 3 to 5, the body part 10 comprises a generally planar base orflange 14 which carries on its front side integral structure providing asample chamber 16 which is closed at its end remote from the base 14 andwhich terminates, in the plane of the base 14, in a port 18 which, inthe preferred embodiment, is rectangular. A funnel 15 extends upwardlyfrom an entrance opening in the sample chamber, whereby a fluid samplecan be introduced into the sample chamber 16. As shown in FIGS. 2 and 3,a resilient gasket, for example of an injection mouldable elastomer,referenced 20 in FIGS. 2 and 3 is carried by the base 14. The gasket 20extends around the port 18 and protrudes slightly rearwardly from therear face of the base 14, for sealing against the adjacent surface ofglass microscope slide (26, FIG. 2). The material of the gasket 20 ispreferably a thermoplastic elastomer such as Evoprene G936, and ismoulded in situ on the backplate, the body 10 and integral backplate 12and the gasket being formed by a two shot injection moulding technique,with the body 10 and backplate being formed in one shot and the gasketbeing formed in the other shot. The gasket incorporates an oil componentwhich, in use, forms a thin oil film on the slide 26 where the gasketcontacts the slide. This film acts as a barrier to the aqueous fluid ofthe biological sample and tends to prevent migration of such fluid, fromthe cell layer deposited on the slide, beyond the boundary defined bythe region of contact of the gasket, after opening of the centrifugationdevice and removal of the side. Subsequent processing of the slide andsample layer generally involves immersion of the slide in an alcoholbased medium which also removes the thin oil film.

The base 14 is generally rectangular, as is the back plate 12, and theliving hinge 22 extends along one vertical edge of the base 14 and theadjacent vertical edge of the back plate 12. The vertical edge of theback plate 12 remote from the living hinge 22 carries a detent 24 forco-operating with elements carried by the body 10 adjacent the edge ofthe base 14 remote from the living hinge 22 and which elements, togetherwith detent 24, form a catch arrangement whereby the back plate may besecured in a closed position on the base 14 with a microscope slide,indicated at 26 in FIGS. 1 and 2, held between the base 14 and the backplate 12. As illustrated in FIGS. 1 and 5, the upper edge of the backplate 12 may be scalloped or recessed, as indicated, to allow readygrasping of the upper edge of the microscope slide 26 between finger andthumb during removal of the slide from the device after centrifugation,as described below.

In use of the device, a microscope slide is located between the backplate 12 and the base 14. (FIGS. 3 and 5 show integral hooks 31 tosupport the lower end of a microscope slide 26 fitted against the frontsurface of the back plate until the back plate 12, with the slide, isclosed against the base 14). In this condition, as illustrated in FIG.2, the gasket 20 engages the adjacent surface of the slide 26 in asealing-tight manner.

The device is then mounted in a centrifuge (not shown) in such a mannerthat bosses 30 projecting from the sides of the back plate act asjournals received in bearings provided by complementary slots inmounting structure within the centrifuge. When the centrifuge is atrest, the device rests in the centrifuge in a position in which theslide 26 is at an angle. When the centrifuge is spun up, the devicepivots about the axis of bosses 30, into a position in which the slideis vertical. When the centrifuge is spun, the centrifugal forcegenerated produces a rapid settling of the cells within the biologicalsample against the surface of the glass slide 26, within an area boundedby gasket 20 and these cells remain in a thin layer on the slide afterthe centrifuge is stopped. In order to ensure a more even distributionof cells across the exposed area of the slide during the centrifugingstep, the sample chamber has a plurality of parallel baffle plates 17extending alternately from opposite sides of the sample chamber,part-way across the latter and generally parallel with the bottom wallof the sample chamber. After the centrifuge is stopped, thecentrifugation device removed from the centrifuge, and the slidecarefully removed after opening of the back plate as described below.

Referring to FIGS. 6, 7 and 8, the fragmentary horizontal section viewsof FIG. 6 and FIG. 7 show a portion of the back plate 12 adjacent theedge carrying the detent 24 and show the adjacent portion of the body 10and a latch 32 which is connected with the remainder of the body 10 byan integral live hinge 34. The detent 24 comprises a head portionconnected with the adjacent edge of the backplate 12 by a relativelyflexible arm 33. The body 10 also carries an integrally formed shieldelement 36 in the form of a generally flat plate which is disposed at apredetermined distance from the adjoining side wall of the body 10 andextends over the latch 32. There is thus defined between the latch 32and the shield element 36 a narrow space through which the detent 24 isprojected in the closed condition of the back plate shown as FIG. 6. Inthis position, an abutment surface of the detent 24, facing away fromthe free end or nose of the detent 24 engages an opposing abutment faceof the latch element 32 and, additionally, the surface of the nose ofthe detent facing away from the shield element 36 is engaged by anopposing surface of the latch 32, afforded by an extension 32A. When theback plate is moved from the open position shown in FIG. 7 to the closedposition shown in FIG. 6, the natural resilience of the living hinge 34causes the latch 32, originally deflected downwards by the nose of thedetent 24, to spring back again into the locking position shown in FIG.6. In this closed position, deflection of the detent 24 away from thepart of the body 10 to which the hinge 34 is attached, being deflectionsuch as would allow disengagement of the detent 24 from the latch 32, isprevented by engagement of the detent 24 with the shield element 36.

As a result of the arrangement described, it is not possible to open theback plate 12 without removal or displacement of the shield element 36which, as described below, necessarily involves rupture of a connectingelement. As indicated in FIG. 8, the shield element 36 convenientlytakes the form of a lever having a free end 36A and pivotally connectedwith a projection 37 from the body 10 byway of an integral living hinge40. The end of the lever 36 remote from free end 36A is secured by anarrow and hence weakened connection 42 to the side of body 10. When itis desired to release the back plate 12 for removal of the slide 26, thefree end 36A of the shield element 36 is pressed manually towards theadjacent surface of the body part 10 causing the opposite end of thelever 36 to break from its connection 42 with the body part 10, allowingthe portion of the element 36 overlying the detent 24 to move away fromthe latter allowing the latch 32 to swing backwards and away from theadjoining side wall of the body 10, with corresponding flexure of thearm 33 of the detent away from said side part. The leg 32A, engaging theopposing surface of the detent 24, has the function of forcing detent 24upwards (as viewed in FIG. 6) as the latch 32 swings backwards, therebyto assist in disengaging the abutment face of the detent 24 from theopposing abutment face of the latch 32. Of course, after fracture of theconnection 42 in the manner described, the latch arrangement cannot beused to hold the back plate 12 in a fully closed position relative tothe body part, thus ensuring that the centrifugation device is a singleuse device.

1. A centrifugation device comprising a combined sample chamber andslide holder adapted to be mounted, with a microscope slide, in acentrifuge in a predetermined position, after placing, in the samplechamber, a fluid biological sample containing cells, the centrifugationdevice comprising an integrally moulded body affording a base adaptedfor engagement with a microscope slide, structure on one side of thebase defining a chamber for a fluid sample, with an opening for theintroduction of fluid to said chamber, the base including an apertureand carrying a means for sealing the edges of such aperture with respectto the surface of a microscope slide placed across the base, or forallowing the passage of liquid but obstructing the passage of cells, thecentrifugation device further including a back plate connected with thebase plate by an integral hinge and a latch mechanism formed integrallywith the remainder of the device and arranged, when the back plate isclosed against the rear of a microscope slide engaged with the base, tolocate the slide between the base and the back plate and to hold theback plate in this closed position until fracture of a retaining elementfrom the integrally moulded body; wherein the latch mechanism comprisesa back plate detent carried by the back plate adjacent a free edge ofthe latter and which, in operation, co-operates in the closed positionof the device, with a complementary latch carried by the body of thedevice and connected with said body by an integral live hinge, the latchmechanism further comprising a shield element which in the condition ofthe device before use, is secured in a position in which it extends overthe complementary latch at a predetermined distance from the integrallive hinge of the complementary latch, the arrangement being such thatin the closed position, with the shield element still attached, the backplate detent is retained between the shield element and thecomplementary latch and the shield element counteracts a turning momentapplied to the complementary latch as a result of tension in the backplate detent, whilst on breaking of a frangible retaining elementholding the shield member in position relative to the device body, theshield element is able to move away from the complementary latchallowing the latter to swing away from the back plate detent for releaseof the back plate detent to allow the back plate to swing away from thebody of the device and to allow removal of the microscope slide.
 2. Acentrifugation device according to claim 1, wherein said complementarylatch is provided with a retaining arm which engages a face of said backplate detent to push the detent across the abutment face of the latch asthe latch tilts outwardly and backwards during the release of the detentafter rupture of the connection of the shield element with the bodypart, and thus to ensure release of the back plate detent from thelatch.
 3. A centrifugation device according to claim 2, wherein saidshield element is in the form of a lever which is pivotally connectedwith said body of the centrifugation device for pivoting about an axisgenerally perpendicular to the pivotal axis of the back plate withrespect to said body defined by said integral hinge and generallyperpendicular to the direction of movement of said detent as it movesinto engagement with said complementary latch, and wherein saidfrangible retaining element normally holds said lever against pivotingbut, once fractured, allows said lever to pivot about its pivotal axisto move the part of said lever adjacent said latch away from said latch.4. A centrifugation device according to claim 3, wherein the pivotalconnection of said lever with said body is also provided by a livingintegral hinge.
 5. A centrifugation device according to claim 3 or claim4, wherein said pivotal connection is intermediate opposite ends of saidlever, said frangible connection is at one of said ends of said leverand said latch is located between said frangible connection and saidpivotal connection, and wherein the other of said end of said lever isfree, whereby said frangible connection can be broken by pressing saidother of said two ends of said lever toward said body portion, to swingsaid one end and the region of the lever between said one end and saidpivotal connection, away from said latch.
 6. A centrifugation devicecomprising a combined sample chamber and slide holder adapted to bemounted, with a microscope slide, in a centrifuge in a predeterminedposition, after placing, in the sample chamber, a fluid biologicalsample containing cells, the centrifugation device comprising anintegrally moulded body affording a base adapted for engagement with amicroscope slide, structure on one side of the base defining a chamberfor a fluid sample, with an opening for the introduction of fluid tosaid chamber, the base including an aperture and carrying a means forsealing the edges of such aperture with respect to the surface of amicroscope slide placed across the base, or for allowing the passage ofliquid but obstructing the passage of cells, the centrifugation devicefurther including a back plate connected with the base plate by anintegral hinge and a latch mechanism formed integrally with theremainder of the device and arranged when the back plate is closedagainst the rear of a microscope slide engaged with the base, to locatethe slide between the base and the back plate and to hold the back platein this closed position until fracture of a retaining element from theintegrally moulded body; wherein the latch mechanism comprises a backplate detent carried by the back plate adjacent a free edge of thelatter and which, in operation, co-operates in the closed position ofthe device, with a complementary latch carried by the body of the deviceand connected with said body by an integral live hinge the latchmechanism further comprising a shield element which, in the condition ofthe device before use, is secured in a position in which it extends overthe complementary latch at a predetermined distance from the integrallive hinge of the complementary latch, the arrangement being such thatin the closed position with the shield element still attached, the backplate detent is retained between the shield element and thecomplementary latch and the shield element counteracts a turning momentapplied to the complementary latch as a result of tension in the backplate detent, whilst on breaking of a frangible retaining elementholding the shield member in position relative to the device body, theshield element is able to move away from said complementary latchallowing the latter to swing away from the back plate detent for releaseof the back plate detent to allow the back plate to swing away from thebody of the device, and to allow removal of the microscope slide;wherein said means for sealing the edges of said aperture comprises anelastomeric gasket carried by said base and encircling said aperture,for engagement with such microscope slide placed across said base.
 7. Acentrifugation device according to claim 6, wherein said elastomer is aninjection moulded elastomer and is moulded in situ with said body in atwo-shot moulding process in which said body and back plate are formedin one moulding shot and the gasket is formed in the other mouldingshot.
 8. A centrifugation device according claim 6 or claim 7 in whichthe material of said gasket includes an oil component which, in use,forms an oil film on the microscopic slide where the gasket contacts theslide, which soon act as a barrier to aqueous fluid and thus tends toprevent migration of such fluid past the region of the slides contactedby the gasket, after opening of the centrifugation device and removal ofthe slide.